Contact lenses are used by an increasing number of people as means of correcting vision and/or compensating for eye abnormalities. Worldwide, about 100 million people use contact lenses. In the U.S. alone, 34 million people wear contact lenses (http://www.medicalpost.com/mpcontent/article.jsp?content=/content/EXTRACT/RAWART/3836/02B.html). However, contact lenses must usually be inserted and removed daily with scrupulous cleaning and disinfection between each wearing that requires solutions and containers.
During wear and normal handling of contact lenses, microorganisms as well as biomolecules such as lipids, proteins, etc., can adhere to the contact lenses and contaminate the storage containers/solution. Furthermore, a tear film that contains proteins, lipids, and even microorganisms covers the surface of the eye. Any of these components found in the tear film, on the external surface of the eye or the surrounding skin, can be carried into the storage containers/solution for the contact lens. Then, the microorganisms that multiplied in the storage containers/solution can transfer to the eyes via contact lenses and become a pathogen that may cause eye infection, resulting in impaired vision and blindness. Various solutions have been developed to clean these deposits and disinfect the microorganisms.
A “daily cleaner” comprised with various kinds of surfactants and disinfectants is recommended for daily use to remove most deposits and debris on contact lenses. In an approach to prevent protein deposits, contact lens solutions containing chemical agents such as cationic polymers were developed to prevent proteins from adhering to the contact lens surface of rigid gas permeable (RGP) and soft contacts lenses.
Solutions that wet the lenses before insertion in the eye are required for both the hard and soft types of contact lenses, although their formulations have tended to differ based on their different properties. After the contact lenses are inserted in the eye, ophthalmic solutions for rewetting, lubricating, and/or enhancing the comfort of the contact lens wearer are sometimes applied to the eye by means of a drop dispenser. Isotonic solutions for improving the comfort of wearing soft contact lenses by being added directly to the contact lens in the eye typically contain viscosity enhancing agents, lubricants, surfactants, buffers, preservatives, and salts.
Multipurpose solutions are popular because of the convenience of a single solution for cleaning, disinfecting and conditioning contact lenses immediately prior to insertion of the lens in the eye. Multipurpose solutions are also designed for use as a wetting agent, without rinsing, meaning that the solution must be ophthalmically safe for eye contact. This limits, to some extent, the type and concentration of both cleaning agents and biocides that can be employed in the solution as a preservative or disinfectant tends to be irritating to the eye. Additionally, the surface active agents must not inhibit the wetting or conditioning function of the solution.
U.S. Pat. No. 4,820,352 (Riedhammer et al.) discloses compositions for cleaning and conditioning contact lenses, where the primary cleaning agent is a specific class of polyethyleneoxy-polypropyleneoxy block copolymer adduct of ethylene diamine (also known as poloxamine). This patent describes compositions which are sufficiently nonirritating that a contact lens treated with the solution can be inserted directly in the eye.
U.S. Pat. No. 5,209,865 (Winterton et al.) discloses a conditioning solution for contact lenses that comprises a combination of a poloxamine and a poloxamer surfactant each having an HLB (hydrophilic-lipophilic balance) of seven or below. This patent describes a solution forming a uniform hydrophilic film on a lens surface for which proteins have very little affinity for a prophylactic effect to the lens.
U.S. Pat. No. 5,604,189 and U.S. Pat. No. 5,773,396 (Zhang et al.) disclose a composition for cleaning and wetting contact lenses comprising (i) a non-amine polyethyleneoxy-containing compound having an HLB of at least about 18, (ii) a surface active agent having cleaning activity for contact lens deposits that may have an HLB less than 18, and (iii) a wetting agent. An ethoxylated glucose derivative such as glucam can be employed as the wetting agent, also disclosed in U.S. Pat. No. 5,401,327 to Ellis et al. In another approach, Tyloxapol is employed as a conventional surface active agent in a multipurpose solution, which agent has cleaning activity for contact-lens deposits and has an HLB less than 18.
There has been a constant need for ophthalmic solutions with better lipid cleaning properties. The deposits from cellular debris, protein, and lipid accumulated over time can adsorb to the surface of contact lenses and irritate the eyes. Particularly, lipid deposits can reduce the transparency and impair the performance of the contact lenses. Lipid deposits on RGP or silicone hydrogel lenses during wear generate a hydrophobic surface that is not easily rewetted with currently used types and concentrations of surfactants in the lens care compositions.
There is, therefore, a need for a composition with improved lipid cleaning properties while maintaining or increasing the biocidal efficacy of the product without adversely affecting comfort or safety in terms of the level of toxicity to eye tissue. It would also be desirable to have a composition that can be utilized as an eye drop, an eyewash solution, a contact lens care solution or a cleaning solution, a storing solution, a disinfectant, a cleaning-storing solution, and a cleaning disinfecting-storing solution. The invention answers these needs.